Place the chicken breasts on a piece of foil that's large enough to wrap around the chicken. Add a sprig of sage, a few pieces of diced onion, a drizzle of olive oil and red wine vinegar. Season with some salt and pepper.
Wrap the foil around the chicken. Grill for about 20 minutes, over direct heat, or until the chicken has cooked through. Cooking time may vary depending on the thickness of the meat.
Serve Grilled Sage Chicken Packets with sliced bread and vegetables.